Fl. Amer. Sept., 219. 1814.
Shrubs, evergreen, 0.1-0.8 (-2) m. Stems monomorphic, without short axillary shoots. Bark of 2d-year stems brown or yellowbrown, glabrous. Bud-scales (13-) 20-44 mm, persistent. Spines absent. Leaves 9-21-foliolate; petioles 2-11 cm. Leaflet blades thin and ± flexible; surfaces abaxially rather dull, smooth, adaxially dull, somewhat glaucous; terminal leaflet stalked, blade 2.9-8.4 × 1.2-4.8 cm, 1.8-3.2 times as long as wide; lateral leaflet blades lanceovate to ovate, 4-6-veined from base, base rounded to cordate, margins plane, toothed, each with 6-13 teeth 1-2 (-3) mm tipped with spines to 1-2.4 × 0.1-0.2 mm, apex acute or broadly acuminate. Inflorescences racemose, dense, 30-70-flowered, 6-17 cm; bracteoles membranous, apex acute, obtuse, or rounded. Flowers: anther-filaments without distal pair of recurved lateral teeth. Berries blue, glaucous, oblong-ovoid or globose, 8-11 mm, juicy, solid. 2n = 56.
Phenology: Flowering winter–spring (Mar–Jun).
Habitat: Open or shaded woods, often in rocky areas
Elevation: 0-1800 m
B.C., Calif., Idaho, Oreg., Wash.
Plants of Berberis nervosa are usually very low (commonly 0.1-0.3 m), but occasional plants may be considerably taller (to 2 m). One such population from north of Westport, California, has been separated as B. nervosa var. mendocinensis. Similar populations occur sporadically throughout the range of B. nervosa, so the form should not be recognized taxonomically.
Berberis nervosa is resistant to infection by Puccinia graminis.
The Skagit tribe used Berberis nervosa medicinally in a root preparation to treat venereal disease (D. E. Moermann 1986).
"thin" is not a number.